An image forming apparatus forms a toner image and moves the formed toner image with an image holding member to transfer the toner image onto a print medium. The image forming apparatus fixes the toner image transferred onto the print medium with a fixing device. For example, the image forming apparatus forms a toner image on a photoconductive drum and enables a primary transfer belt as an image holding member to receive the toner image from the photoconductive drum. The toner image received by the primary transfer belt is transferred onto the print medium at a transfer nip where the print medium and the primary transfer belt contact with each other.
The image forming apparatus includes an image quality adjustment sensor for detecting a density of the toner image on the image holding member. The image forming apparatus adjusts the density of the toner image on the image holding member based on a detection result of the image quality adjustment sensor.
The image forming apparatus includes a passage sensor that detects whether or not the print medium reaches a secondary transfer position (transfer nip). The image forming apparatus determines whether or not the print medium reaches the transfer nip based on a detection result of the passage sensor. If it is determined that the print medium does not reach the transfer nip, the image forming apparatus stops the operation and makes a notification that a jam occurs.
However, in order to detect the density of the toner image and the passage of the print medium, the image forming apparatus needs to include both the image quality adjustment sensor and the passage sensor, resulting in an increase in cost and complexity.